As known, thermotropic liquid crystal polymers containing a cyclohexyl unit are described in numerous examples in the literature.
Generally, the cyclohexylic unit is derived either from 1,4-cyclohexandicarboxylic acid or from 1,4-cyclohexandiol.
In U.S. Pat. No. 4,342,862, polyesters are derived from polycondensation of an acidic mixture containing trans-1,4-cyclohexandicarboxylic acid and other aromatic diacids with substituted hydroquinones such as methyl, phenyl and chloro hydroquinones.
The preparation of thermotropic liquid crystal polyesters by polycondensation of the only trans-cyclohexandicarboxylic acid with some of the above mentioned substituted hydroquinones is described in "Macromolecules", vol. 19, p. 1824 (1986).
Polyesters of trans-1,4-cyclohexandiol with substituted aromatic diacids or alternatively polyesters derived from mixtures of cis and trans isomers of 1,4-cyclohexandiol with aromatic or cycloaliphatic diacids are described in the same article.
Other thermotropic liquid crystal polymers containing a cyclohehexane unit are the block copolyesters described in "Macromolecules", vol. 14, p. 1626 (1981), such as for instance polyoxy-trans-1,4-cyclohexylenoxycarbonyl-trans-1,4-cyclohexylencarbonyl-o xy-1,4-phenylenoxyphthaloyl or the copolymers described in "Makromolecular Chemie 187", p. 1145 (1986), wherein the rigid structure of trans-1,4,cyclohexanedibenzoate is polycondensed with .alpha.,.omega.-alkandioic acids.
All the preceding references are hereby incorporated by reference.